As the state of the art computer processors become ever more powerful, their switching speeds are increasing, and there is a significant problem of processor overheating.
Existing solutions for cooling computer processors are proving inadequate to meet the heat dissipation requirements upon them, and this problem is becoming more serious as time passes.
The heat generated by a working CPU is a function of the density of transistors (CMOS devices) in the chip and of switching speed. Each CPU model had several versions of switching speed, and the switching speed and temperature were correlated.
The processors of early personal computers such as Intel's XT, 286 and 386 chips don't need heat dissipation. Their power consumption is low and they do not generally overheat. The more powerful and more recent 486 CPU chip needs a small heat sink, (generally an aluminium plate attached to the chip), to draw heat away from the chip and to facilitate its dissipation.
The Pentium CPU needs a heat sink and a fan to allow it to perform properly. The improved Pentium II model has a different structure, and is more powerful, and consequently generates more heat requiring dissipation. This CPU (and others such as the AMD Athlon CPU model) need a very large heat sink and fan, and sometimes two fans or more. As processors become ever more powerful, the need for more efficient cooling systems that are able to cope with increasing cooling demands is becoming more acute.
Since increasing the operating temperature of a CPU critically affects its reliability, and thus the reliability of the entire computer system it is a part of, the currently available cooling technologies are stretched to their limit. To enable further improvements in the computing power of personal computers it is necessary to further increase switching speeds.
To achieve this, it is imperative to decrease the CPU temperature.
Conventional cooling systems may be considered as being ‘passive’ systems. By this, it is meant that they remove heat from the CPU of the computer system allowing its temperature to approach the ambient temperature of the computer's surroundings. Since passive cooling solutions have evolved to a capability that is close to the theoretical limit for this type of technology, a new solution is needed.
Back in May 1996, an attempt was made by Marlow Industries, Inc., Dallas, Tex., USA, to provide an active cooling solution for preventing CPUs from overheating. Their solution was a simple device which was been marketed as their Model ST3404 PC chip cooler, and included a DT12-4 Thermoelectric cooler having a small heat sink. The cooler was mounted adjacent to the PC chip, and was coupled to the motherboard. It provided heat dissipation of up to 10 Watts and had a power input limit of 5 Volts DC, according to the manufacturer's data sheet. The Marlow device is powered by the power supply of the computer, hence has limited capabilities. Since it cannot receive sufficient power to dissipate the heat generated by current processors, its heat dissipation capacity is too low to meet the requirements of present day CPUs. Because of its inherent disadvantages, particularly it not being able to meet the cooling demands of later generations of CPUs power requirements, the Marlow device ceased to be marketed by the beginning of the year 2000. Its demise was linked to the availability of larger, passive cooling systems comprising heat sinks and fans that were more efficient than this small active cooling system.
Non-controlled thermoelectric units deliver maximum cooling under all conditions, including when the CPU is using low power or in“sleep mode”. Overcooling may result in water vapour condensing on the unit's cold side, and this can lead to serious problems, particularly in some climates having high ambient temperatures and humidity levels.
Today, processors, such as the Pentium 4, XP ATHLON, TITANIUM, and others, produce 70 Watts or more of heat that requires to be dissipated to prevent the processors from overheating. Each successive generation of processors has a higher chip density and generates ever larger quantities of heat requiring dissipation. Current solutions, based on passive heat sinks and fans, are only just able to cope with currently available processors, enabling them to function reliably and stably. They will be unable to handle the expected heat dissipation demands of the next generation of processors.
Even when the average temperature of the processor is kept within acceptable limits, “hot spots” (local areas of high temperature within the processor), can cause instability, processor failure and damage. The average processor temperature achieved with current passive cooling solutions (consisting of a heat sink and fan) leaves only a small margin between the working CPU temperature and the maximum temperature permitted. In consequence, hot spots may cause serious problems. It is anticipated that as successive generations of processors will generate more heat, the problem of hot spots will become increasingly critical. A larger margin between the working CPU temperature and its maximum permissible temperature is required to protect from overheating, to ensure reliable, stable, operation, and to eliminate the need for slowed down processing, as practiced by the TCC function of the Intel Pentium 4 processor.
There is thus a need for new cooling systems for CPUs having higher heat dissipation ability than currently available systems. The present invention described hereinbelow, addresses this need.